Electrical contactor



Feb. 14, 1939. D, ELLIS ET AL 2,147,430

v ELECTRICAL CONTACTOR Filed Aug 28, 1936 3 Sheets-Sheet 1 0 V R O- INVENTORS George G Armszrang I an D6] 6 Ellis.

" Feb. 14, 1939. D. ELLIS ET AL 2,147,430

ELECTRICAL CONTACTOR Filed Aug. 28, 1936 3 Sheets-Sheet 2 George G. Armstrong and Sgiber EZZIS.

,Mw. 451W Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE burg, Pa., assignors & Manufacturing Company,

Pa., a corporation of Application August 28,

8 Claims.

Our invention relates to magnetically-actuated switches adapted for use in alternating-current circuits and it has particular relation to imprcvements in the design and Construction of means which extinguish the arc incident to a separation of the switch contacts by forcing it into a deionizing chamber.

Generally stated, the object of our invention is to provide a contactor type of switch having high interrupting capacity which is compact in design.

A more specific object is to increase the power interrupting capacity of electrical contactors which have arc-extinguishing means of the de ionizing chamber class.

Another object is to lower the cost of manufacture, lengthen the life and facilitate a replacement of the arc-box structure which positions the deionizing chamber adjacent to the path of switch-eimtact travel.

A further object is to improve the design and utility of the magnetic means or blow-out coil which impels the are into the deionizing chamber of the arc box.

A still further object is to improve the battling means through which the arc gases escape from the top of the box.

Our invention itself. together with additional objects and advantages. will best be understood through the following description of specific embodimcnts when taken in conjunction with the accompanying drawings in which:

Figure l is a perspective view of a contactor quip ;-..l with arc-extinguishing means incorporating the several improvements of our invention.

Fig. 2 is a view in side elevation of one of the arc-extinguishing structures utilized by the device 01 Fig. 1.

Fig. 3 is a section view taken along the line III of Fig. 6 showing the internal construction of the arc box of Fig. 2.

Fig. 4 is a view of-one of the two gas-battle plates which form a part of our improved arc box.

Fig. 5 is aview of one of the several metal plates or grids which are spacedly positioned in the deionizing chamber of the arc box.

Fig. 6 is a representation of the arc box removed from the contactor and viewed from the end which abuts the contact-carrying panel thereof.

Fig. 7 is a sectional view taken along the line VII-VII of Fig. 8 showing other details of the internal construction of the box.

to Westinghouse Electric East Pittsburgh, Pennsylvania 1936, Serial No. 98,324

Fig. 8 is a top plan view of the arc box of the preceding figures, and

Figs. 9 and 10 are respectively top plan and perspective views of the molded refractory shell which constitutes the main structural member 5 of our improved arc-box.

The contactor represented in Fig. l of the drawings as being equipped with our improved arc-extinguishing means is a three-pole device of the shaft-driven vertical-lift type. It com- 10 prises an inverted U'-shaped frame l6 which sup ports contacts (0 stationarily from its upper portion through a panel member 24 and cooperating movable contacts l2 rotatably from the lower end of its two legs through bearing pins 28 and a shaft bar 26. The frame also supports the contact; actuating magnet l430-32 from the side of one of its downwardly extending legs. The armature or movable portion 30 of this magnet is attached to one end of the shaft bar 26'. A winding 14 carried by the stationary core 32 serves to magnetize the magnet core parts.

This unit or self-contained form of contactor construction is more completely described by our copending application, Serial No. 98,322, filed August28, 1936. In it the frame I5 is adapted to support the completely assembled device from a mounting panel or other supporting structure not shown). The construction of the illustrated E-core vertical lift magnet is also more completely shown and described by our copending application, Serial No. 98,323, filed August 28, 1936. I

The circuit to be controlled by the contactor is connected with the stationary members I0 35 through lugs 20 and with the movable contacts l2 through flexible shunts 22. As long as the magnet winding III is deenergized, gravity holds the armature 30 in the lowermost position illus trated in which the movable contacts are sepa- 0 rated from the stationary contact members.

Energization of the magnet winding attracts the armature upwardly. This movement rotates the shaft bar 26 into the contact engaging position, thereby completing the controlled circuit. Springs 33 give resiliency to the connections between the bar 26 and the movable contacts l2.

Deenergization of the magnet winding releases the armature 30 and, by action of gravity and the compressive force of springs 33, it is urged downwardly causing contacts I! rapidly to separate from embers Hi. This interrupts the controlled circuit.

Associated with each set of an arc box 23 supported by a contacts Ill-l2 is blow-out coil 25.

point of its current wave. This deionizing chamber contains a series of spaced metallic plates or grids 38 having tapered notches alined to form a \igshaped groove (see Fig. 7).

The magnetic action of the blow-out coil forces the are into the apex of this groove andthence into the space traversed by the plates. This ""breaks the original are up into a series of short arcs which move along the plate surfaces until extinguished. All of the above happens within an interval of time which is short as compared with the half period of the controlled alternating-current circuit.

Our invention resides in improvements in the design and construction of this type of arc-extinguishing equipment. The first of these is the provision of a blow out coil 25 which is adapted mechanically to support the arc box 23 in operat3ive position on the contactor (see Figs. 1, 2 and This improved coil comprises two single-turn loop portions of fiat-section conductor which respectively are positioned on either side of the contact members l0 and I2 in planes parallel to that defined by the path of travel of the movable member l2. The coil may be punched from a fiat sheet of copper or other metal. The original punching constitutes a fiat closed link of metal.

To form the final structure each of the side portions of this link is bent through a right angle with respect to a common central portion which is attached tothe panel member 24 of the contactor by screws 52. When so installed, the coil constitutes the electrical connection between the stationary contact member l0 and its associated terminal stud 20.

The controlled circuit current than divides between the two parallel side portions of the coil.

' The resulting magnetic interactions are such that any are drawn between the contacts 10 and I2 is urged upwardly away from the contacts. This action is aided by the effect on the arc of the loop or doubling back shape in the circuit formed by the contact members.

In addition to producing magnetic forces which impel the arc upwardly away from the contacts l0 and I2, the two parallel projecting sections of the blow-out coil 25 are adapted to receive the arc-box 23 therebetween and there securely to hold it in operative position with respect to the contacts. The fit is a slidable one which permits of a ready detachment of the 1 are box. 'This facilitates repair and replacement.

When the box has been slid into the position shown in Fig. 1, its weight is supported by the top portions of the blow-out coil sections. The attachment is aided by a metal yoke 44 which surrounds the box in the manner illustrated and serves mechanically to strengthen it. The side portionsof this yoke are adapted to cooperate with the outer sides of the blow-out coil 25. Its side portions are shaped to interfit with the outer sides of the blow-out coil 25. Its upper edges are shaped to interfit with notches in the tops of the blow out coil sections. These sections fit between the yoke sides and the arc box 23.

The yoke 44 may also be stamped from a fiat sheet of steel or other metal. The side portions of the original stamping are then bent through right angles with respect to a common central portion and the resulting structure fitted over the box 23. A rivet 54 secures it in place. The

"spring action of the yoke sides assists in holding the arc box in place on the blow-out coil structure.

In order to remove the arc box from the con 'tactor, it is merely necessary to pull out the lower portion thereof, lift the box upwardly a short distance, and then completely withdraw from engagement with the side portions of the blow-out coil. 'The first of the above operations disengages depressions 46 in the inner side of the yoke 44 from projections 48 on the outer sides of the blowout coil 25. The resulting tilting and upward movement then releases the top portion of the box yoke from the notches in the upper part of the supporting members 25 and permits the arc box completely to be withdrawn.

In installing the arc box the above procedure is reversed. The upper portion is first pushed all the way between the blow-out coil sides and the lower portion then pushed downwardly and inwardly; This locks the 'box securely in position.

Preferably the yoke 44 is made of steel or other magnetic material in order that it may also perform an electrical function. We have discovered that a presence of this magnetic material in the position illustrated concentrates the fields generated by the blow-out coil 25 and the arc and that this concentration materially in-v creases the speed of arc travel into the deioniz ing chamber. Hence the construction described. Slots 56 provided in the side portions of the yoke prevent it from short-circuit'ing the blow-out coil turns.

In the arrangement illustrated the blow-out coil 25 functions to reverse the field both below the contacts Ill-:42 and above the deionizing grids 38. This prevents the are from blowing out at the bottom of the box 23 and also restrains it from passing through the tops of the grids.

Another improvement of our invention resides in the provision of an arc-box 23 which is of the construction shown in Fig. 10. The material used is preferably a heat-resisting asbestos-base or other refractory substance which may be moulded into the'form illustrated. This portion is completely closed on three of its sides and partially so on the fourth. It has top and bottom openings of the form shown. It may either be of the onepiece design shown or consist of two or more sections which are held in place by the yoke 44. Advantages are that emission of arc flame is prevented and constructional clearances may be made small and uniform.

When installed in place on the contactor, the sidewalls of the box effectively insulate the device contact members from the closely spaced sections of the blow out coil 25. This makes for greater compactness.

In orderto support the weight of the V- notched deionizing plates 38, the inner walls of the arc box are provided with wide ledges 66 upon which the lower ends of the plates rest. The box walls above these ledges are provided with rib projections 64 which position the grids 38 in the spaced relation illustrated. The fitting may be made so close. as to allow practically no movemcnt. It may further be improved by the use of a bonding cement. In this manner all wear of the supporting surfaces of the box is eliminated.

To assist in transferring the are from the contacts l0 and I2 into the deionizing chamber occupied by grids 38, front and rear arc horns 58 and 60 may also be positioned inside of the box in the manner best shown in Fig. 3. As the arc is drawn from the contacts, the magnetic action of the blowout coil efiects a quick transfer to these horns and thence into the deionizing plates 38. A central arc horn 62 may also be used to divide the main arc into two sections before it reaches the chamber. The use of these horns raises the speed of arc extinction and increases interrupting capacity. The relatively wide bottom tips of the grids 38 make them more resistant to burning off by the arc.

Preferably the deionizing plates 38 and are horns are made of steel or other magnetic material. This we have found speeds the transfers of the are from the contacts into the deionizing chamber. The magnetic quality of the material also prevents the series of short arcs from leaving the grid ends. Another important result of this quality is that it intensifies the magnetic field produced by the arcs and thereby aids in moving them along the plate surfaces.

The box 23 is arranged to receive the grids 38 and arcs horns 58, 60 and 62 from its top. When in place, these members are held sufliciently tight so as to prevent their moving and wear of the supporting surface is in this manner eliminated.

In some cases it may be desirable to use a bonding.

cement to improve their fitting.

A further feature of our invention resides in improved venting means in the top of the arc box 23 which allow an escape of the arc gases while confining all fiame to the box interior. These comprise two fibre plates 40 and 42. The construction of each is best shown in Fig. 4. The lower plate 42, when installed is positioned a short distance above the tops of the deionizing grids 38. It is here supported by an engagement of its edge projections with the lower ledges 10 of the box top (see Fig. 10).

The upper plate 40 is ofidentical construction, but is reversed so that its slots or openings are staggered with respect to those of the lower plate. It is positioned a short distance, above the lower plate by an engagement of its-- edge projections with the higher elevation ledges 12 in the box top. Each of the plates is preferably held in position by the use of cement applied between its edges and the side walls of the chamber.

The bailie plates 40 and 42 are preferably made of fibre, inasmuch as this material in itself has good are extinguishing characteristics. We have observed that the use of fibre plates substantially increases the rupturing capacity of the equipment over that obtainable by the use of other materials. However, for applications in which operation is so rapid as to cause high arc-box temperatures, a refractory material is of especial advantage.

In order that the gas pressure may be equalized along the entire length of the stack of deionizing grids 38, we form small depressions in the top portions thereof. These depressions are best shown by the views of Figs. 5 and 7. One effect is to increase the effective spacing between the grid tops and the under surface of the lower baffle plate. Another effect is to prevent the are directly from striking the lower plate.

Although we have shown and described certain specific embodiments of our invention, we are fully aware that many modifications thereof are possible. Our invention therefore is not to be restricted except insofar as it is necessitated by the prior art and by the scope of the a pended claims.

We claim as our invention:

1. In a circuit controlling device having a pair of relatively movable contact members, a combined blow-out coil and are box support comprising a pair of loops formed of flat sections of conductor positioned on opposite sides of the contact members in planes parallel to that of the contact movement, and a detachable arc box provided with reces s therein to slidably interfit said loops.

2. In an electrical contactor device, a pair of relatively movable circuit controlling contact members, a blow-out coil comprising a pair of flat-section conductors bent to form separate loops positioned on opposite sides of the contact members, an arc box adapted to fit between and be supported by said loops, and a metal yoke surrounding a portion of said are box and having side portions adapted to cooperate with the outer surfaces of the aforesaid loops.

3. In an electrical contactor device, a pair of relatively movable contact members, a pair of loops of fiat-section conductor positioned on opposite sides of the members to constitute a blowout coil, an arc-box adapted to fit between and be supported by said conductor loops, and a yoke of magnetic material surrounding said are box to concentrate the magnetic field produced by the blow-out coil.

4. Are blow-out means disposed to be operated in conjunction with a circuit interrupting device having a pair of relatively movable contact members comprising a pair of conducting loops included in the circuit through which the contact current flows and positioned on opposite sides of the contact members in planes parallel to the movement thereof, an arc box adapted to fit between and be supported by the conducting loops and provided with means for interlocking the box and conducting loops to retain the box in fixed position hereon.

5. In a circuit controlling device having a pair of relatively movable contact members, are blow-out means comprising a pair of conducting loops included in the circuit through which the contact current flows and positioned on opposite sides of the contact members in planes parallel to the movement thereof to define a path in which an are drawn between said contact members is magnetically positioned, an arc box adapted to fit between and be supported by the conducting loops and provided with means for interlocking the box and conducting loops to retain the box in fixed position thereon, said are box containing a series of spaced metal plates positioned along the path in which the arc is magnetically positioned by said conducting loops for cooling and extinguishing the arc.

6. In a circuit controlling device having a pair of relatively movable contact members, are blow-out means comprising a pair of conducting loops included in the circuit through which the interictking the box and conducting loops to retain the box in fixed position thereon, said are box containing a series of spa'ced metal plates positioned along the path in which the arc is magnetically positioned by said conducting loops for cooling and extinguishing the arc, the'end plates, at least, of the series extending adjacent the pair of movable contact members, re-

spectively, to form arc horns for assisting the travel of the are into the path of the metal plates.

'7. In a circuit controlling device having a, pair of relatively movable contact members, an arc box positioned above the contact members and containing a series of spaced metal plates therein for cooling and extinguishing the arc, means comprising a pair of conducting loops included in the circuit through which the contact current flows and positioned on opposite sides of the contact members in planes parallel to the movement thereof so constructed and arranged as to drive the arc frorn the contact membersto a positionjvithin the plates and restrained from passing beyond the tops of the plates.

8. In a circuit controlling device having a pair of relatively movable contact mcmbcrs,- an arc box positioned about the contact members and containing a series 01' spaced metal plates therein extendingalong-a horizontal path adjacent the top thereof for cooling and extinguishing the arc, the end plates, at least, of the series extending adjacent the pair of movable contact members respectively to form arc horns for assisting the travel of the are into the path of the metal plates, means comprising a pair of conducting loops included in the circuit through which the contact current flows and positioned on opposite sidescf the contact members in planes parailel to the movement thereof so constructed and arranged as to drive the are from the contact members-to a position along the path of the plates and restrained from passing beyond the tops of the plates.

v DELBERT- ELLIS.

GEORGE c. ARMSTRONG. 

